The present invention relates to acyclic machines of the type using liquid metal collectors, and more particularly to an improvement for retaining the liquid metal in such machines.
Radial type acyclic motors and generators generally include a metallic disk rotor rotating on a shaft between electromagnetic stator poles excited by field coils wound concentric with the shaft. Instead of solid brush, current collectors at the rotor periphery, liquid metal collectors are sometimes used to close the electrical current loop between the shaft and the rotor, and an inert pressurized cover gas fills the gaps between the rotating components and the stationary housing. Ideally, the liquid metal is confined to the outermost area of the rotor, however, the gaps on the sides being quite small--on the order of 50 mils--the motion, particularly at high speeds, induces a recirculating radial flow of the gas along the housing. Some of the liquid metal becomes entrained in the inwardly flowing gas and may leak out of the machine. The depletion of liquid metal eventually causes an electrical discontinuity in the current loop at the collector. Various methods for recovering or confining the liquid metal have been used such as mechanical seals, stepped rotor and housing geometries or so called "rain gutters". U.S. Pat. No. 4,106,616 to Burton D. Hatch for example centrifically separates the entrained liquid metal from the cover gas by allowing the mixture to flow into a central chamber or gutter within the rotor from which it can return to the collector within the rotor. However, these devices generally decrease the electromechanical performance of the machine.